1. Field of the Invention
The present invention relates to blowout preventers having rams for sealing around wireline. This invention particularly relates to a manually operated blowout preventer in which the rams may be inverted.
2. Description of Related Art
Blowout preventers are included in lubricators connected to wellheads to maintain pressure control of the well during well servicing operations. Opposed rams in prior blowout preventers close and seal on wireline running through the preventer and are oriented to prevent well pressure from below the rams from flowing upwardly out of the well. A key attached to each ram moving in a slot in the body is used to keep rams oriented and ram sealing faces in alignment for sealing on each other and around wireline when rams are moved inwardly to close and seal.
The following are examples of blowout preventers using keys attached to the rams, which are slidable in slots in the preventer body, to orient the rams to seal well pressure from below. The rams in these preventers cannot be inverted and operated to close and seal and prevent pressure from above the rams to flow into the well.
U.S. Pat. No. 4,214,605 issued to William D. Hardgrave July 29, 1980, for "ACTUATOR FOR WIRELINE BLOWOUT PREVENTER". This patent discloses a blowout preventer having a hydraulic actuator which utilizes well pressure to move the rams to closed position and pressurized control fluid for moving the rams to open position. The hydraulic actuator includes mechanical means for assisting in closure and locking the blowout preventer in closed position.
U.S. Pat. No. 4,325,534 for "MANUALLY OPERATED BLOWOUT PREVENTER AND HYDRAULIC OPERATOR THEREFOR", issued to James T. Roark and Steven R. Hayter Apr. 20, 1982. This patent covers a manually operated blowout preventer which is converted to power operation by adding structure which includes hydraulic motors for turning the ram stems to move the rams between open and closed positions.
Another U.S. Pat. No. 3,692,316 issued to Thomas R. Bishop and Archie W. Peil Sept. 19, 1972 for "WIRELINE BLOWOUT PREVENTER". This patent covers a blowout preventer in which the rams may be moved between open and closed positions either manually or hydraulically. The rams of this blowout preventer have structure for guiding wireline into a centered position on the ram sealing surfaces as the rams move toward each other to seal on wireline in closed position.